In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal. Image sensors can largely be divided into charge coupled devices (CCD) and CMOS image sensors.
Using CMOS fabricating technology, a CMOS image sensor can be fabricated using a simple fabrication process that consumes a relatively small amount of power and consists of a comparatively small number of photo processing steps.
Also, because a control circuit, signal processing circuit, analog/digital conversion circuit, etc. can be integrated into one CMOS image sensor chip, the product can be easy to miniaturize.
FIG. 1 is a sectional view of a CMOS image sensor according to the related art.
Referring to FIG. 1, a p-type epitaxial layer 11 is grown on a p-type semiconductor substrate 10 divided into device isolation regions and active regions. A device isolation layer 12 is formed on the device isolation regions of the semiconductor substrate 10, so that the active regions are divided into a first, second, and third n-type region 13, 14, and 15 by the device isolation layer 12.
Here, the first, second, and third n-type regions 13, 14, and 15 are photodiode regions.
Then, gate electrodes 17 are formed on the active regions of the semiconductor substrate 10 with a gate insulating layer 16 interposed therebetween. Insulating layer sidewalls 18 are formed on the sides of the gate electrodes 17, and an interlayer insulating layer 19 is formed on the entire surface of the semiconductor substrate 10 including the gate electrodes 17.
A first planarizing layer 20 is formed on the interlayer insulating layer 19, and a blue, green, and red color filter layer 21 is formed on the first planarizing layer 20 with color segments corresponding to the first, second, and third n-type regions 13, 14, and 15.
Also, a second planarizing layer 22 is formed on the entire surface of the semiconductor substrate 10 including each of the color segments in the color filter layer 21, and microlenses 23 corresponding to each color segment are formed on the second planarizing layer 22.
In the CMOS image sensor according to the related art having the above configuration, light is incident through each color segment of the color filter layer 21 on the corresponding first, second, and third n-type region 13, 14, and 15 (or the photodiode region).
However, the light that passes the blue, green, and red color segments can interfere with neighboring color segments, inducing a loss in the quantity of light that is focused on the photodiodes through dispersion and diffraction of the light passing through the segments of the color filter.